Grant editor permissions to external user on shared calendar

Pascal Lorch 6 Reputation points


i try to implement a customer request for a shared calendar. I need to share the calendar with an external company, which have no user in the customers domain. The problem is, that i need to grant the external company user the possibilitty to add entries in the sahred calendar.
I can add permissions to the user, but only the free/busy sharing policies seems to be to configure.
As i try to set permissions in powershell:


In the organization settings in the m365 admin center, i only see the calendar setting for external sharing (also free / busy sharing only).

So is it possible to share a shared-mailbox calendar with an external user in combination with the possibility for the external user to add an change appointments??

Thanks in advance

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  1. Michael Barranco 10 Reputation points

    I know its been some time since this question was asked. Just curious if the limited permissions were still the only option? Only Free/Busy or LimitedDetails, always read-only.

    I too have a client seeking editor permissions for an external user. Was only seeing that the next best option may be sharing calendar via sharepoint or teams?

    2 people found this answer helpful.

  2. Vasil Michev 90,881 Reputation points MVP

    External permissions can only be read-only, there is no way to add Editor permissions. If you need such, you need to create an account for the external user within your organization, then grant the permissions.

    1 person found this answer helpful.

  3. Joyce Shen - MSFT 16,631 Reputation points

    Hi @Pascal Lorch

    For the error you get when running the command set-mailboxfolderpermission, that's because there is no existing permission entry found for user.

    You could firstly check the permission for this:

    Get-MailboxFolderPermission -Identity "\Calendar" | ft Identity,FolderName,User,AccessRights  

    If no result found, the solution is to use the Add-MailboxFolderPermission cmdlet when there are no access rights in place for that user.

    Add-MailboxFolderPermission -Identity "\Calendar" -User "" -AccessRights Editor  

    Here is an article introduces this error: Set-MailboxFolderPermission – There is no existing permission entry found for user
    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    In addition, for sharing in o365, we could refer to the official document which lists different scenarios: Sharing in Exchange Online

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